Projection-type image display device and projection-type image display system

1. A projection-type image display device of front projector type comprising: an image light generator configured to generate image light; a projection optics configured to project the image light onto a screen, the projection optics including a projection lens configured to project the image light which is output from an image light generator, and a reflection mirror configured to reflect and condense the image light toward the screen and located closest to the screen side on an optical path of the image light which is output from the image light generator, wherein a protective cover is provided on an optical path of the image light reflected by the reflection mirror so as to cover at least the outer side of the projection lens and the reflection mirror, wherein the protective cover covers the projection optics and has a limited transmissive region transmitting the image light reflected by the reflection mirror, and wherein the transmissive region of the protective cover is disposed in a position where the image light is condensed by the reflection mirror so that the area of the transmissive region is minimized to be smaller than the light incident plane of the protective cover so that the shape in area is similar to the cross section of the condensed light beam.

2. The projection-type image display device according to claim 1 , wherein the protective cover has an opening communicating from the reflection mirror side to the screen side and the transmissive region is the opening.

3. The projection-type image display device according to claim 2 , wherein the transmissive region is a point that corresponds with a focal point for light passing through the transmissive region and projected onto the screen.

4. The projection-type image display device according to claim 1 , wherein at least one portion of the protective cover is formed of a light-transmitting member and the transmissive region is formed of the light-transmitting member.

5. A projection-type image display system of front projector type comprising: a screen; an image light generator configured to generate image light; a projection optics configured to project the image light onto the screen, the projection optics including a projection lens configured to project the image light which is output from an image light generator, and a reflection mirror configured to reflect the image light toward the screen and located closest to the screen side on an optical path of the image light which is output from the image light generator; and a protective cover provided on an optical path of the image light reflected by the reflection mirror, wherein the protective cover covers at least the outer side of the projection lens and the reflection mirror and has a limited transmissive region transmitting the image light reflected by the reflection mirror, and wherein the transmissive region of the protective cover is disposed in a position where the image light is condensed by the reflection mirror so that the area of the transmissive region is minimized to be smaller than the light incident plane of the protective cover so that the shape in area is similar to the cross section of the condensed light beam.

6. The projection-type image display system of front projector type according to claim 5 , wherein the transmissive region is a point that corresponds with a focal point for light passing through the transmissive region and projected onto the screen.